The centrifugal machine is generally of the type disclosed in prior U.S. Pat. Nos. 2,878,993; 3,050,238; 3,179,333; 3,231,183; 3,231,185; 3,233,880; 3,494,543; 3,770,190; 3,809,375; 3,814,307; and 3,904,109. In practice, present machines manufactured by applicant's assignee utilize ducts which are secured to one of the seives and have sidewall openings which distribute material supplied to the ducts by the feed tubes for the phases. This method of distributing the light and heavy phase liquids is not as satisfactory for larger size contactors, and particularly contactors of increased axial width. Some of the difficulties encountered with the present method are the difficulty of sealing the ducts to the feed tubes and sealing the ends of the ducts. The use of a multiplicity of feed tubes also introduces difficulties in such systems.